In Defense of Fluoride

Response to North article of 10/3/2017

In a recent Lund Report, commenter Rick North stated a myriad of half-truths in regard to the public health initiative of water fluoridation. So, let’s sort things out, and bring the issue back into reality

1. North notes the recent Bashash, et al., Mexican study of the effects on children, of prenatal fluoride exposure to pregnant moms. Unlike the authors of this study, North completely omits the stringent limitations of this study, as are clearly stated in the study itself. These limitations include:

A. A lack of data on urinary fluoride content of pregnant women living in fluoridated areas of the United States. Fluoridation opponents seek to do what the authors, themselves, did not urinary fluoride content of one population with non-existent data of another.

“Finally, our ability to extrapolate our results to how exposures may impact on the general population is limited given the lack of data on fluoride pharmacokinetics during pregnancy. There are no reference values for urinary fluoride in pregnant women in the United States” 1

B. Insufficient information to rule out significant confounders.

“Nevertheless, it is not possible to entirely rule out residual confounding or in the population as a whole (that might have been detected had we had full data on larger sample sizes) or bias (should the subpopulations that had the data for analysis have a different fluoride–cognition relationship than those participants who were excluded from the analyses).” 1

C. There was no significant effect noted by fluoride exposure on children after birth.

“Finally, in models that focused on the cross-sectional relationship between children’s exposure to fluoride (reflected by their specific gravity–adjusted urinary fluoride levels) and IQ score and that contained the main covariates of interest, there was not a clear, statistically significant association between contemporaneous children’s urinary fluoride (CUFsg) and IQ either unadjusted or adjusting for MUFcr.” 1

D. Evidence suggested that IQ effects were noted only with prenatal urinary content above 0.8 mg/L.

“The associations with GCI appeared to be linear across the range of prenatal exposures, but there was some evidence that associations with IQ may have been limited to exposures above 0.8 mg/L.” 1

E. Results would need to be replicated by independent researchers.

“Our findings must be confirmed in other study populations, and additional research is needed to determine how the urine fluoride concentrations measured in our study population are related to fluoride exposures resulting from both intentional supplementation and environmental contamination.” 1

F. “Other limitations include the lack of information about iodine in salt, which could modify associations between fluoride and cognition; the lack of data on fluoride content in water given that determination of fluoride content is not reported as part of the water quality monitoring programs in Mexico; and the lack of information on other environmental neurotoxicants such as arsenic.” 1

G. Bashash, et al., utilized the “spot” collection method of urine collection, rater than the more accurate 24 hour method.

As noted by Deena Thomas, second author of Bashash, et al:

“The spot urine samples we measured cannot account for diurnal variations in urinary fluoride. Previous studies report fluctuations in concentration by time-of-day42 which means that the fluoride levels in our samples could be influenced by the time-of-collection or by diet.” 2

Additionally, in her doctoral thesis, Deena Thomas, using the exact data as did Bashash, reported on the effects of prenatal fluoride on children aged 1, 2, and 3. She found no significant effect on these children. Bashash, chose to omit these findings, and instead began their IQ assessment in children 4 years of age.

Obviously, Bashash, et al. had the same data as did Thomas, so why did they omit any reference to children below the age of 4?

From Thomas’ dissertation:

“Conclusions: This analysis suggests that maternal intake of fluoride during pregnancy does not have a strong impact on offspring cognitive development in the first three years of life.” 2

2. As can be clearly noted, while the Bashash study cannot be dismissed, it is not, at this point, applicable to optimally fluoridated water in the United States. Additionally, as the authors themselves have stated.......this is but one study. It must be kept in perspective with several other quality studies which have found there to be no association of optimally fluoridated water with neurodevelopment or IQ.

a. Broadbent, et al. found:

“These findings do not support the assertion that fluoride in the context of CWF programs is neurotoxic”

While North is certainly welcome to his personal opinion of the quality of this study, he has no qualifications which would render him capable of properly assessing scientific study, in the absence of appropriately cited supporting evidence....of which he has none.

The Broadbent study was peer-reviewed and published in the highly respected Journal of Public Health. 3

c. Mang Li, et al found that “certain low dose of fluoride intake may play a potential protective rather than harmful role in cognitive functions; however, high fluoride exposure is a potential risk factor for cognitive impairment.” 4

d. In 2016, Aggeborn and O ̈hman found no evidence that fluoride levels below 1.5 mg/l have any negative effects. 5

2. In regard to North’s out-of-context quotes from the 2006 NRC:

The The 2006 NRC Committee on Fluoride in Drinking Water was charged to evaluate the adequacy of the EPA primary and secondary MCLs for fluoride, 4.0 ppm and 2.0 ppm respectively, to protect against adverse effects. The final recommendation of this Committee was for the primary MCL to be lowered from 4.0 ppm. The sole reasons cited by the Committee for this recommendation were the risk of severe dental fluorosis, bone fracture, and skeletal fluorosis, with chronic ingestion of water with a fluoride content of 4.0 ppm or greater. Nothing else. Had this Committee deemed there to be any other concerns with fluoride at this level, it would have been responsible for stating so and recommending accordingly. It did not.

Additionally, the NRC Committee made no recommendation to lower the secondary MCL of 2.0 ppm. Water is fluoridated at 0.7 ppm. one third the level which the 2006 NRC Committee on Fluoride in Drinking Water made no recommendation to lower. 6

In March of 2013, Dr. John Doull, Chair of the 2006 NRC Committee on Fluoride in Drinking Water made the following statement:

"I do not believe there is any valid, scientific reason for fearing adverse health conditions from the consumption of water fluoridated at the optimal level”

---John Doull, MD, PhD, Chair of the National Academy of Sciences, National Research Council 2006 Committee Report on Fluoride in Drinking Water. 7

3. The 2012 meta-analysis to which North refers was a 2011 review of 27 Chinese studies dug out of obscure Chinese journals by researchers Phillippe Grandjean and Anna Choi. These studies were of the effects of high levels of fluoride (as high as 11.5 ppm) in the well-water of various Chinese, Mongolian, and Iranian villages.

By the admission of Grandjean and Choi, themselves, these studies had key information missing, inadequate control for confounders, and questionable methodologies. These 27 studies were so seriously flawed that Grandjean and Choi were led to issue a public statement in March, 2013 that the studies should not be used to judge water fluoridation in the US. This obviously has not stopped fluoridation opponents from doing so anyway.

"These results do not allow us to make any judgment regarding possible levels of risk at levels of exposure typical for water fluoridation in the U.S. On the other hand, neither can it be concluded that no risk is present. We therefore recommend further research to clarify what role fluoride exposure levels may play in possible adverse effects on brain development, so that future risk assessments can properly take into regard this possible hazard."

--Anna Choi, research scientist in the Department of Environmental Health at HSPH, lead author, and Philippe Grandjean, adjunct professor of environmental health at HSPH, senior author. 8

4. In the 2014 Lancet article to which North refers, Grandjean and Landrigan briefly mentioned that fluoride is an environmental neurotoxin. They based this opinion on the 27 Chinese studies of 2012 meta-analysis which, as has been previously addressed, had far too many serious flaws to have any applicability to fluoridated water in the US.

A complete refute of this Lancet article may be viewed in a subsequent Lancet article:

5. North makes reference to the most recent meritless petition filed with the EPA by the antifluoridation faction ”FAN” and other antifluoridation groups. In its 40 page rejection of the petition, EPA reviewers, citing facts and evidence, systematically dismantled all of the arguments of the petitioners, while providing detailed explanation of the irrelevance, invalidity, and misrepresentation by petitioners, of the “196 peer-reviewed studies” noted by North. The complete rejection document may be found on the Federal Register:

As is the law, the petitioners were free to appeal the EPA rejection in federal court, which they elected to do. This appeal by the petitioners contains nothing but unsubstantiated anecdotal claims by fluoridation opponents, along with the same arguments and studies which the EPA had already dismantled. The seeming belief by the petitioners that the court will accept meaningless anecdotes, and find some alternative set of facts to inject credibility into their claims is ludicrous.

6. Fluoridation opponents have tried endlessly to attach fluoride in water to a safety factor of 10. As humans have been ingesting fluoride in water since the beginning of time. In the entire 72 year history of fluoridation, there have been no proven adverse effects of fluoride at the level at which water is fluoridated. Therefore, suddenly proclaiming there to be a need of 10 fold margin of safety with optimally fluoridated water is nothing more than another attempt to inject unnecessary requirements into a public health initiative which has clearly demonstrated, over 7 decades, there to be no need for such.

7. Fluoridation opponents seek the sudden cessation of a very valuable public health initiative, which has provided significant dental infection prevention for hundreds of millions of individuals over the past 72 years. As such, it is incumbent upon these activists to provide valid evidence to support their request. They have provided no such evidence.

8. Attempts to link water fluoridation to smoking are a tactic used frequently by fluoridation opponents. Obviously smoking has no relevance, whatsoever, to this public health initiative.

9. Had the 2006 NRC Committee deemed “thyroid disease, kidney disease, and diabetes” to be of concern with fluoride at the level of 4.0 ppm or below, it would have been responsible for so stating in its final report, and recommending accordingly. It did not.

10. In regard to North’s concern with controlling fluoride intake from fluoridated water, when the maximum amount of a substance which can be ingested falls below the threshold of adverse effects, then amount is of no concern in regard to adverse effects. This is true for fluoride, chlorine, ammonia, and myriad other substances routinely added to public water supplies. Prior

to approaching the threshold of adverse effects of fluoride from optimally fluoride in conjunction with all other normal sources of fluoride exposure, water toxicity would be the concern, not fluoride.

11. North makes reference to people consuming different amounts of water. This is of no concern with optimally fluoridated water. Simply put, water is fluoridated at 0.7 mg/liter (ppm=mg/liter). Thus, for every liter of fluoridated water consumed, the "dose" of fluoride intake is 0.7 mg. The average daily water consumption by an adult is 2-3 liters per day. The US CDC estimates that of the total daily intake, or "dose", of fluoride from all sources including dental products, 75% is from the water.

The US Institute of Medicine has established that the daily upper limit for fluoride intake from all sources, for adults, before adverse effects will occur, short or long term, is 10 mg. As can be noted from a simple math equation, before the daily upper limit of fluoride intake could be attained in association with optimally fluoridated water, water toxicity would be the concern, not fluoride.

The range of safety between the minuscule few parts per million fluoride that are added to existing fluoride levels in your water, is so wide that "dose" is not an issue.

The choice is easy. Heed the overwhelming consensus opinion of the worldwide body of respected science and healthcare, or heed the half-truths of fluoridation opponents such as Rick North and his close affiliate, the New York antifluoridation faction “FAN”.


1 Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6–12 Years of Age in Mexico

Bashash, Thomas, et al.

Environ Health Perspect; DOI:

2 Fluoride exposure during pregnancy and its effects on childhood neurobehavior: a study among mother-child pairs from Mexico City, Mexico

DB Thomas

Doctoral Dissertation

University of Michigan 2014

Page 38

3 Community Water Fluoridation and Intelligence: Prospective Study in New Zealand

Jonathan M. Broadbent, PhD, W. Murray Thomson, BSc, PhD, Sandhya Ramrakha, PhD, Terrie E. Moffitt, PhD, Jiaxu Zeng, PhD, Lyndie A. Foster Page, BSc, PhD, and Richie Poulton, PhD

(Am J Public Health. Published online ahead of print May 15, 2014: e1–e5.

4 Cognitive Impairment and Risk Factors in Elderly People Living in Fluorosis Areas in China

Mang Li 1 & Yanhui Gao1 & Jing Cui1 & Yuanyuan Li 1 & Bingyun Li 1 & Yang Liu1 &

Jing Sun1 & Xiaona Liu1 & Hongxu Liu1 & Lijun Zhao1 & Dianjun Sun

Biol Trace Elem Res (2016) 172:53–60

5 Aggeborn, L., & Öhman, M. (2016). The Effects of Fluoride In The Drinking Water.

6 Fluoride in Drinking Water: A Scientific Review of EPA's Standards 2006

7 Doull statement

8 Grandjean/Choi statement

Steven D. Slott, DDS

Communications Officer

American Fluoridation Society

News source: 


“This is a very rigorous epidemiology study. You just can’t deny it. It’s directly related to whether fluoride is a risk for the neurodevelopment of children. So, to say it has no relevance to the folks in the U.S. seems disingenuous.” - Dr. Howard Hu, Dean of the Dalla Lana School of Public Health at the University of Toronto (2017)

The NIH/NIEHS/EPA sponsored study seems to have been designed to disprove the dozens of human studies among the hundreds of general neurotoxicity that document an adverse prenatal impact on cognitive-behavioral development which include a lowering of IQ - but did the opposite. Using sophisticated evaluation of individual prenatal fluoride doses consistent with doses consumed by the the general American and Canadian populations living in fluoridated communities, the study validated that prenatal exposure to fluoride in low doses do in fact lower IQ on a dose-response trend line.

This highly focused 12-year US government sponsored study that was conducted by renowned experts in environmental health did NOT evaluate other neurological evidence of increased learning disabilities, let alone the impact on the developing immune system which is also at risk from prenatal exposure - all of which are also supported by medical science.

But let's make this simple: Given the amount of science documenting an adverse cognitive impact of a known enzyme poison characterized as a 'developmental neurotoxicant' by 21st century scientists, do you want to volunteer your pregnant wives, sisters, and daughters living in fluoridated communities for another 12 year study?

Once,again, Dr. Steve Slott exposes the cherry-picked, deceptive propaganda of Rick North, the mouth of the the Fluoride Action Network in Oregon. Thank you, Lund Report, for printing Dr. Slott’s essay so quickly.

For all of Dr. Slott’s many words, he still seems unable or unwilling to understand the crux of what I said.

You can’t - with any logic or scientific integrity - insist fluoridation is harmless, ignoring a constantly growing database of hundreds of peer-reviewed studies documenting fluoride’s toxicity and calling for further investigation.Yet this is exactly what the U.S. government and fluoridationists have done for decades.

“Proven safe” and “More research is needed” are oil and water. You can’t have it both ways.

Dr. Slott argues that mothers and fathers should have to risk diminished intelligence in their unborn children by drinking fluoridated water.

I don’t agree. This is the fundamental difference in our perspectives.

As for specifics, it’s quite simple to rebut each of his points, but three can serve as examples of his writing strategy.

First, he says that the Institute of Medicine determined that 10 mg of fluoride per day for adults is the daily upper limit “before adverse health effects will occur” and uses this as his argument that “dose is not an issue.”

Dose is not an issue? With a known poison?

Let’s do an accuracy/reality check. First, the IOM’s figure (which is questionable itself) is for people age 8 and older – it’s completely irrelevant to harming unborn children. Second, the 10 mg was only referring to skeletal fluorosis – none of the other numerous health risks linked to fluoride. This was certainly not the impression of his words.

The other unmentioned inconvenient truth is that people also ingest fluoride from many other sources – swallowed toothpaste, drinks, processed foods, pesticide residues, air pollution, etc. The toxic dose adds up, and it all starts with the water.

Then there are the double standards. He highlights that the U. of Toronto study had potential confounders not accounted for, such as iodine and arsenic (although there are no known levels of toxic arsenic in the Mexico City area where the subjects lived).

Yet when he cites the Broadbent New Zealand study as the best example of fluoride not lowering IQ, he fails to mention that it also didn’t account for iodine and arsenic. Nor did he mention that the U. of Toronto study measured twelve confounders while Broadbent measured only four. Of course, regardless of the confounders, Broadbent’s study is virtually meaningless from the start because total fluoride exposure between the two groups being compared was nearly the same.

Finally, quotes from three of the expert scientists on the 12-person NRC committee, after they’d completed their three-year review, paint a far different picture of fluoridation than Dr. Slott’s:

Robert Isaacson, PhD (dec.): “I had no fixed opinion on whether or not fluoride should be added to drinking water . . . The more I learned the more I became convinced that the addition of fluorides to drinking water was, and is, a mistake.”

Hardy Limeback, DDS, PhD: “In my opinion, the evidence that fluoridation is more harmful than beneficial is now overwhelming.”

Kathleen Thiessen, PhD: “Elimination of community water fluoridation at the earliest possible date would be in the best interest of public health.”

And we’re supposed to believe that there’s an “overwhelming consensus” on fluoridation’s safety?

You don’t need to be a scientist to know otherwise.


“All of Dr. Slott’s words” are what it takes to properly address unsubstantiated claims and misrepresented science put forth by fluoridation opponents who place little value on truth or accuracy.

1.  Having no scientific background, North, as would be expected, does not understand scientific study.  There are well over 56,000 fluoride studies listed by PubMed.  Within the scientific literature, one can find a study to support just about any theory, i.e. :

The question is not whether there are studies claiming this adverse effect, or that adverse effect, from fluoridation, but of  the quality, interpretation, validity, and relevance of such studies.  In order to view a prime example of how fluoridation opponents misrepresent scientific study, one only need read the EPA rejection of the most recent meritless petition filed with that agency by “FAN”.  As  their “evidence” the petitioners cited many of that “growing database of hundreds of peer-reviewed studies....”.  In its 40 page rejection, EPA reviewers explained in detail the invalidity, irrelevance, and misrepresentation by petitioners of those studies.  This EPA document may be viewed in entirety on the Federal Register:

2.  One would be hard pressed to find any legitimate researcher who will not state  that further study is needed on any scientific issue.  Such study should never cease.  That this is recommended does not mean that an initiative is, in any manner, unsafe.  Humans have been ingesting fluoride in water since the beginning of time.  In the entire 72 year history of fluoridation, hundreds of millions having chronically ingested optimally fluoridated water during that time, there have been no proven adverse effects.  There can be no more clear demonstration of the safety of an initiative than that.

3. “Dr. Slott” has never  “argues that mothers and fathers should have to risk diminished intelligence in their unborn children by drinking fluoridated water.”  What Dr. Slott has said is that there is no valid, peer-reviewed scientific evidence of any risk to “diminished intelligence”, or any other adverse effect from optimally fluoridated water.  Unsubstantiated claims, speculation, and wishful thinking by fluoridation opponents do not constitute valid evidence of anything, and certainly are no reason to deprive entire populations of the benefits of a very valuable public health initiative.

4.   Fluoridation opponents frequently claim that they could rebut my claims, but......”.  The fact is that if North could rebut my claims, he would.  To do so would require valid facts and evidence to support his rebuttal, which do not exist.

5.   In typical fashion, North dishonestly quotes me  out-of-context to appear to support his claims.  What I have stated, in complete and proper context,  in regard to dose is that when the maximum amount of a substance which can be ingested falls below the threshold of adverse effect, then dose of that substance  is not an issue in regard to adverse effects.  If North can demonstrate how dose is of concern toward adverse effects when the maximum dose which can be ingested falls below the threshold of adverse effects, then I urge him to do so.

6. In regard to North’s half-truth “reality check”......first, his unsubstantiated claim that the IOM figure of 10 mg is “questionable itself” is typical of the groundless claims fluoridation opponents constantly put forth as “fact”.  Given the track record of no proven adverse effects in hundreds of millions of humans who have chronically ingested optimally fluoridated water over the past 72 years, there is nothing to suggest that the IOM established daily upper limit is, in any manner, “questionable itself”.  

Second, yes, the IOM daily upper limit is considerably less for children 8 years and below.  However, the only reason for this lower limit is chance of mild dental fluorosis in developing teeth. Nothing else.  This is clearly obvious by the fact that the teeth develop during the years of 0-8.  If there were some concern other than dental fluorosis, there would not be such a clear demarcation at 8 years.

7. The filtered and edited misinformation on “fluoridealert”, notwithstanding, the IOM daily upper limit is in regard to any adverse effects, not simply skeletal fluorosis.  Skeletal fluorosis is just the first that would manifest.  Given that skeletal fluorosis is so rare in the 74.5% fluoridated US as to be nearly non-existent, obviously the 10 mg daily upper limit before adverse effects is valid in regard to “any other health risks”.

8. In regard to other sources of fluoride intake, does North honestly believe that the US EPA, the US DHHS, and the US IOM are so uninformed as to not take total fluoride exposure into account when setting maximum daily upper limits, maximum allowable amount in water, and optimal amount in water?  It may come as a surprise to North and other fluoridation opponents but these factors have long been since considered before this argument dawned on opponents.

9. The critiques I provided of the Bashash Mexican study were those of the authors of that study themselves, as evidenced by  the quotes  I provided.  North’s critiques of Broadbent are nothing but his own, unqualified, unsubstantiated personal opinions. 

10.  Consensus, by definition, does not mean unanimous.  Yes, there were 3, long term, outspoken fluoridation opponents on that 12  member NRC Committee.   However, it is a mystery how North seems to somehow consider these 3 personal opinions to equally counter that of the US CDC, the US EPA, the US IOM, the American Dental Association, the American Medical Association, the World Health Organization, the American Academy of Pediatrics, the Deans of the Harvard Schools of Medicine, Dentistry, and Public Health, the past 6 US Surgeons General, and over 100 more of the most highly respected healthcare and healthcare-related organizations in the world.  

Yes, there is overwhelming consensus of the safety and effectiveness of fluoridation, amongst the worldwide body of respected science and healthcare.

Steven D. Slott, DDS

Communications Officer

American Fluoridation Society